How Much Does a Window AC Cost to Run?
A window air conditioner can be inexpensive or surprisingly costly to operate depending on its electrical input, efficiency, runtime, and electricity rate.
Start with watts
Look for the electrical input or wattage on the unit’s label or manual. For an example, assume a window AC uses 1,000 watts while operating.
That is 1 kW because 1,000 watts ÷ 1,000 = 1 kW.
Example at $0.16 per kWh
At eight hours per day, continuous operation would use:
1 kW × 8 hours = 8 kWh per day.
At $0.16 per kWh:
8 × $0.16 = $1.28 per day.
For 30 days, that would be $38.40 if the unit actually consumed 1 kW continuously for eight hours every day.
Continuous power is not the same as real-world use
The example above is intentionally simple. A thermostat can cause the compressor to cycle, so the average electrical consumption over an entire hour may be lower than the maximum running input.
Factors that change the cost
- Cooling capacity and electrical input.
- Energy efficiency.
- Room size and insulation.
- Outdoor temperature.
- Temperature setting.
- How often the compressor cycles.
- Your utility rate structure.
Calculate your own window AC cost
Use our Electricity Cost Calculator and enter the wattage from your unit, your average daily runtime, number of days, and your actual electricity rate.
Ways to reduce operating cost
Keep doors and windows closed while cooling, clean filters according to the manufacturer’s instructions, reduce unnecessary heat entering the room, and choose a reasonable temperature setting. These steps do not change the electricity rate, but they can reduce how hard or how long the AC needs to operate.
Bottom line
The cheapest window AC to run is not necessarily the one with the lowest purchase price. Compare the electrical input and expected operating pattern, then calculate the running cost using your own electricity rate.